Moving From Microsoft SQL Server to ClickHouse: Can a Microsoft Team Make the Switch to Open Source?

By Ordinal Science · 2026-09-10

Let's start with a scenario. A mid-sized company has a couple hundred employees. For many years, it has been a Microsoft shop. Its data lives in Microsoft SQL Server, and its IT team knows that world inside and out.

And it has worked well. Until recently.

The company started collecting new kinds of data, and a lot of it. Event logs and transaction histories grew to sizes nobody had planned for. Queries that used to take seconds started taking minutes. Hardware upgrades helped for a while, but the costs kept climbing. So did the licensing bills.

SQL Server is a solid product. But it was built mainly for running a business day to day. It was not designed to scan billions of rows for analytics.

The team started looking at ClickHouse. ClickHouse is an open source database built for exactly this job. It stores data by column instead of by row. When you want the average of one field across a billion records, ClickHouse only reads that one field. The result is fast queries on very large data.

The decision makers liked what they saw. The performance gains were clear. The licensing cost was low or zero.

But one question kept coming up. Can our team actually make this switch?

This is a real worry. And it is a fair one. Moving from Microsoft to open source is not only a technical change. It is a cultural one.

In a Microsoft shop, you buy a product, and you get a vendor. If something breaks, you know who to call. The tools look and feel alike. Many staff hold Microsoft certifications and have built careers around that knowledge.

Open source works differently. Here are some of the changes teams tend to worry about.

Support looks different. There is often no single company standing behind the product. Help may come from forums and documentation. Paid support exists, but you have to choose it and set it up yourself.

The environment may be new. Many open source tools run best on Linux. Some setup happens through configuration files rather than menus and wizards.

The mindset shifts. In open source, teams often take more ownership. They read the docs and test things themselves. That freedom is useful. But it can feel like a lot of responsibility at first.

The SQL is slightly different. ClickHouse uses SQL, but with its own functions and quirks. People who know T-SQL, Microsoft's flavor of SQL, will feel at home quickly. They will still need to learn some new habits.

These are the reasons many companies stay put, even when their current tools no longer fit.

Here is the good news. Making this move is much easier today than it was ten or fifteen years ago.

Open source is no longer on the edge of the industry. It has become one of the main sets of tools that companies choose from. Even Microsoft has changed. It owns GitHub, the largest home for open source projects, and now runs SQL Server on Linux. Many Microsoft-trained engineers already use open source tools without thinking about it.

Support has grown up too. ClickHouse has a large community and detailed documentation. It is also available as a managed cloud service, and commercial support is an option.

And the old tools still connect. ClickHouse works with common reporting tools, including Power BI. A team can keep its familiar front end and swap out the engine underneath.

In this scenario, the company brought in Ordinal Science to help with the deployment. We treated training as part of the project, not an extra at the end. Here is how we approached it.

We built on what they already knew. The team had strong SQL skills. We showed them how that knowledge mapped to ClickHouse and pointed out the key differences.

We kept training hands-on. The team rebuilt some of their own slow reports in ClickHouse using real company data. Seeing a report go from minutes to seconds did more for confidence than any slide deck.

We ran old and new together. For a period, SQL Server and ClickHouse ran in parallel so the team could check that the numbers matched. Nobody had to bet everything on day one.

We made support clear. We wrote plain-language guides for common tasks. We also helped the company choose its support options going forward. Everyone knew who to turn to when something went wrong.

We handed over gradually. Our role shrank step by step as the team took on more.

Moving from a Microsoft ecosystem to open source tools is a real concern for many companies. The worries about culture and support are valid. But they can be overcome. Open source is now a standard part of the modern data world. And a team that knows SQL Server already has many of the skills it needs.

With the right preparation, the switch becomes less of a leap and more of a step. And on the other side is a system that can handle the data the business has today, and the data it will have tomorrow.